I'm attempting to change some settings, such as "Time & Date", from a remote client (NX). There's no problem working remotely on the server. However, in Elyssa, there is now an "unlock" button that must be activated for any settings changes, which I can't get to highlight, in order to make changes from the remote client.

Would I need to add a new "user", or change some permissions for this on the server side?

We were able to fix this behavior by changing Control Center/Authorizations/freedesktop/systemtoolsbackends/Manage System Configuration "anyone" to "Admin Authentication" (was originally set to "no").

Seems to work fine on NX Gnome sessions now (in addition to NX shadowed sessions, which always worked). We are using NoMachine's free server, and I should add that we are actually using Mint 6, rather than XFCE, but we came across this thread while debugging the same problem you described.

You're welcome. We're really liking Mint. Went back and forth trying to decide between Mint and PCLOS (which is also good) but eventually decided on Mint partly because of all the help available in the Mint and Ubuntu forums. Mint 6 seems nicely thought out.